Ministers were last night accused of 'incompetence and insensitivity' after it was revealed that a list of war dead compiled for MPs and Her Majesty's coroner had missed out dozens of dead British soldiers.

Professor Sheila Bird, who discovered the 'forgotten soldiers' during a detailed study of the military inquest system for the Medical Research Council, said the government appeared to have lost track of the actual date of death of the fatally injured soldiers.

Families of troops killed in Afghanistan and Iraq last night reacted with outrage amid calls for an inquiry into the 'disappeared' dead soldiers.

Corroborative analysis by Tory MP Patrick Mercer of ministerial statements concerning the death toll suggest that as many as 33 dead British soldiers literally vanished from the list of fatalities awaiting inquests given to parliament by defence and justice ministers.

Maureen Shearer, who waited more than 550 days for an inquest verdict into her son Richard's death in Iraq from a roadside bomb, said: 'From the MoD's point of view there might be a lot of soldiers who have died, but for anyone to just go missing is ridiculous. It's bad enough to feel that your son died for no good reason, but to feel they were not even cared about to the extent they disappeared is dreadful. I cannot imagine how it must be for parents whose sons literally disappeared in every sense.'

Rose Gentle, who had to wait more than 1,150 days for a coroner's verdict into the death of her teenage son Gordon, also killed by a roadside bomb in Iraq, described the news as 'disgraceful' and 'insensitive'.

Sheila Bird, a vice-president of the Royal Statistical Society and scientist with the Medical Research Council, conducted the study to analyse the length of delays of military inquests. However, she discovered that the list compiled by ministers to inform parliament of the numbers of Britain's war dead awaiting inquests was 'incomplete'.

She said that ministers may have lost track of personnel because of the sheer length of military inquest waiting times, or when a board of inquiry into a fatality had been convened, therefore postponing the inquest date. 'There are a variety of reasons, but it might be that ministers had not appreciated the extent of inquest waiting times and that could partly explain why these casualties went missing. But it is particularly important that when we are talking about service personnel who have given their lives for their country we get it right', said Bird, whose previous study, published in the Journal of the Royal United Services Institute, caused embarrassment for defence officials by revealing that the army was dismissing the equivalent of almost a battalion of soldiers every year for taking drugs.

Details of her latest research for the Medical Research Council's statistical unit arrive in the wake of a grim week for the British army during which the death toll in Afghanistan reached 102 with five paratroopers killed. The latest two casualties, Lance Corporal James Bateman, 29, and Private Sean Doherty, 20, were shot dead last Thursday while patrolling in Helmand province. In Iraq a further 176 UK troops have died since the start of operations in 2003.

Bird's study was launched last autumn when she contacted the Oxford coroner, the closest to RAF Brize Norton, where the bodies of British soldiers are repatriated, to obtain details of inquests concerning casualties in Iraq and Afghanistan. Her report states: 'It quickly became apparent that the list of deaths which the Oxford coroner's office was working with was incomplete - not all military fatalities in Iraq and Afghanistan featured on it. The time to sort this out was liable to be an undue burden on the coroner's office. Moreover, lists being tabled by ministers were likewise incomplete'. She said no blame could be attached to the Oxford coroner; instead questions of 'competence' should be directed towards those who collated figures for the government at the time.

Mercer, a former army officer who has campaigned to help speed up delays concerning military inquests, said that problems may have arisen because the conflict in Iraq was the first time a British government had been responsible for granting inquests to large numbers of war dead. 'It appears to have been difficult for the government keeping day-to-day track of the numbers who have died,' he said. 'But they have a dead body, name and regiment, they know where they were killed and where the death certificate was issued. But it must be said that things have improved considerably.'

A spokesman for the MoD said that problems associated with the military inquests system had now been resolved following extra funding to coroners and the introduction of a dedicated inquest unit. 'Together these have significantly reduced the time between death and inquest. Ministers attach significant importance to reducing the time taken for inquests to be heard. While efforts are made to reduce unnecessary delays, elements such as the comprehensive police investigation and the date set by the coroner are beyond the control of the MoD.' He said that, of the 278 deaths in Iraq and Afghanistan, 199 inquests were now complete, with 52 in 2008 alone. By contrast, Bird's analysis of 90 military casualties between March 2003 and May 2005 found that almost half of the families involved had to wait more than 1,000 days for an inquest verdict.